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Dear all, <br>
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<p><i> As the EGU session GD1.3 draws near</i><br>
<i> We invite you to join us, never fear</i><br>
<i> On the Earth's asthenosphere, a layer so dear</i><br>
<i> Merry Christmas, happy New Year!</i><br>
<br>
<i> Mark Richards is our invited speaker, he's the best</i><br>
<i> He'll talk about the asthenosphere, put the rest to the
test</i><br>
<i> As we come together we'll learn, discuss and explore</i><br>
<i> The mysteries of the Earth, and much more</i><br>
<br>
<i> It's Christmas time and all is well</i><br>
<i> We celebrate the Earth and all it can tell</i><br>
<i> From geodynamics to plate tectonics, we'll see</i><br>
<i> A holistic view of Earth and its history *</i></p>
<p>I hope you enjoy our EGU-Christmas carol, with which we would
like to draw your attention to our EGU 2023 session, entitled -
<b><i><span class="link-coloured"><i>GD1.3: </i>Structure,
chemistry and dynamics of the asthenosphere: an
interdisciplinary look at an essential layer in Earth
system.</span></i></b><i class=""> </i><span
style="font-style: normal;" class="">This session is being
organized by</span> Ingo Stotz, Hans-Peter Bunge, Kaj Hoernle,
Sergei Lebedev, and myself. More info can be found here: <span
class="share-link-container link-coloured active"> <a href="https://protect-au.mimecast.com/s/r6W3CwV1vMfL4WOGrIqzuuP?domain=meetingorganizer.copernicus.org" class="share-link d-none d-lg-inline" title="Copy to
clipboard" moz-do-not-send="true">https://meetingorganizer.copernicus.org/EGU23/session/46081</a>
and the abstract is below. </span></p>
<p>Our invited speaker is Mark Richards (University of
Washington). <br>
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<p>Please consider submitting an abstract (deadline January 10th,
2023).<br>
</p>
Best regards,<br>
Ingo and Berta on behalf of all conveners<br>
<p><b>Abstract:</b></p>
<p>The asthenosphere is a crucial layer in Earth system. Its
importance for interpreting isostasy, postglacial rebound and
the seismic low velocity zone has long been recognized. But a
string of recent results has highlighted its critical
contribution to maintaining plate tectonics, enabling long
distance geochemical heterogeneity transfer, inducing
intra-plate volcanism, and influencing the pattern of upper
mantle seismic anisotropy. A variety of inferences suggest an
asthenosphere perhaps ~100–200 km thick with a viscosity
contrast of ~100–1,000 relative to the deeper mantle. Such a
layer is most effective in promoting plate-like surface motions
by reducing horizontal shear dissipation of mantle flow. Also,
flow within this layer may be driven by the plates (Couette
flow), or pressure-driven from within the mantle (Poiseuille
flow), depending upon the degree to which plates locally inhibit
or drive the underlying mantle. The description of asthenosphere
flux through Poiseuille/Couette flow is particularly powerful,
because it links mantle flow to geologic observables, such as
plate motion changes and variations in dynamic topography. The
latter are coming into focus through an array of innovative
geologic techniques that include thermochronological methods,
studies of river profiles, sediment provenance, landform
analysis, or hiatus mapping at interregional and continental
scale.<br>
<br>
This session will provide a holistic view of the asthenosphere,
its temporal and structural evolution, geochemical heterogeneity
(as sampled by mid-ocean ridge volcanism, mantle xenoliths and
obducted ultra-mafic massifs) and links to the other components
of Earth system. We welcome contributions from seismic
tomography and anisotropy, petrology and geochemistry, plate
kinematics, thermochronological studies, structural geology,
post glacial rebound and geodynamic models that address
questions surrounding the asthenosphere. Studies using a
multidisciplinary approach are particularly encouraged.</p>
<p><font size="2">* by Ingo, Berta and openAI</font><br>
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